In the combustion of fuel, for example coal, oil, peat, waste, natural gas, etc in a combustion plant, such as power plant, a process gas comprising among other components, carbon dioxide in large amounts. The negative effects of carbon dioxide on climate change are well known and there is a strong demand on reducing the emissions of carbon dioxide generated. This demand applies not only to the different power plants as above but also other situations and other industries where CO2 is generated in their processes or by their energy consumption, for example in the cement industry and steel industry. There are a lot of different methods and arrangements for reducing the carbon dioxide emission.
However, common for the methods is that the separation of carbon dioxide from exhaust gases generated in the different industrial plants as above are energy demanding and costly and there is a need to find more efficient ways.
In one of the methods for capturing CO2, known as regenerative calcium cycle (RCC), the separation of CO2 from the flue gas may take place by capturing via a combined carbonation and calcination cycle. In such methods, lime (CaO) may be used as a sorbent agent for the carbon dioxide, forming carbonate of calcium (CaCO3) during the so called carbonation reaction. The formed CaCO3 is subsequently regenerated by heating, whereby the so called calcination reaction produces carbon dioxide and CaO.
A method and system for a regenerative calcium cycle (RCC) is described in U.S. Pat. No. 6,737,031. More specifically, a method for capturing sulfur dioxide (SO2) and carbon dioxide (CO2) is described therein. For capturing of the carbon dioxide the method comprises steps wherein the carbon dioxide present in the flue gases is captured by carbonization in the hearth and then released by decarbonization and the carbon dioxide released is transferred for further treatment or storage.
Although an RCC system, e.g. as described in U.S. Pat. No. 6,737,031, can be made more energy efficient than other available systems for carbon capture and storage, it still carries a negative impact on the overall efficiency of the power plant. There is a need for improved RCC systems that further reduce the impact on the overall efficiency of the power plant.